#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main() {
    int a[5];
    int i = 0, sum = 0;
    float b = 0;
    while (i < 5) {
        scanf("%d", &a[i]);
        sum += a[i];
        i++;
    }
    b = sum / 5.0;
    printf("%.1f", b);
    return 0;
}